Cutting device for an ultrasonic vibration system

ABSTRACT

A cutting device for an ultrasonic vibration system comprises an elongated tool having a cutting edge formed on the front end thereof, and a torsional transducer attached to the tool body at a nodal point of vibration thereof, as well as, if necessary, an amplifier horn is positioned between the tool body and transducer, so that the torsional transducer serves to apply an elastic vibration to the tool body.

United States Patent Shimizu et al.

CUTTING DEVICE FOR AN ULTRASONIC VIBRATION SYSTEM Inventors: MasamiShimizu; Akio Jindai, both of Tokyo, Japan Assignee: Citizen Watch Co.,Ltd., Tokyo,

Japan Filed: June 20, 1973 Appl. No.: 371,855

Foreign Application Priority Data June 23, 1972 Japan 47-62929 U.S. Cl82/36 R, 29/DIG. 46, 82/DIG. 9 Int. Cl B23b 29/04 Field of Search82/DIG. 9, 36 R, 36 A;

51/59 SS; 29/DIG. 46,96

References Cited UNITED STATES PATENTS Calosi et al. 82/DIG. 9 X

[ Jan. 14, 1975 3,056,320 l0/1962 Findley, 29/DIG. 46

3,580,136 5/197l Bodine 90/64 FOREIGN PATENTS OR APPLICATIONS 602,8016/1948 Great Britain 5l/59 SS 1,087,440 2/1955 France 82/DIG. 9

Primary Examiner-J. M. Meister Assistant ExaminerW. R. Briggs Attorney,Agent, or Firm-Ernest G. Montague; Karl F. Ross; Herbert Dubno [57]ABSTRACT A cutting device for an ultrasonic vibration system comprisesan elongated tool having a cutting .edge formed on the front endthereof, and a torsional transducer attached to the tool body at a nodalpoint of vibration thereof, as well as, if necessary, an amplifier hornis positioned between the tool body and transducer, so that thetorsional transducer serves to apply an elastic vibration to the toolbody.

3 Claims, 6 Drawing Figures PAFENTEBJWMW v SHEET 2 [IF 2 CUTTING DEVICEFOR AN ULTRASONIC VIBRATION SYSTEM SPECIFICATION The present inventionrelates to a cutting device for an ultrasonic vibration system mainlyused in a lathe and having a cutting tool elastically vibrated in acutting direction.

It has been well known that ultrasonic vibration can be applied to acutting tool body in a cutting operation so as to reduce the cuttingresistance and thereby obtain a product having a smooth surface andprolong the tool life.

FIG. 1 indicates an ultrasonic vibrator for a prior-art cutting deviceoperative with bending vibration as one of several systems usinglongitudinal vibration, torsional vibration or bending vibration. Inthis case, a longitudinal vibration generated by means of a transducer12 is amplified by a horn 13 and applied to a point located at thecenter of a vibration wave defined for a cutting tool body 11 as shownin FIG. 1, and at which the horn 13 is coupled to the tool body 11. Thetool body 11 is supported by setting pins attached thereto at two nodalpoints of vibration and undergoes transverse vibration on a neutralplane 17 on which are positioned the nodal points of vibration, so as tovibrate a chip in a cutting direction as the cutting edge of said chip15, which is attached to the front end of the tool body 11, engages thesurface of a workpiece l6 rotated.

Since the longitudinal vibration of the transducer involved in thiscutting device must be directed parallel to a direction to which thecutting edge of the chip is vibrated, such an ultrasonic vibrationsystem can not be used in an automatic lathe having a plurality of tools21 to 25 positioned as illustrated in FIG. 2, because the cutting devicedoes not have space sufficient to allow the transducer to be installedbetween the tool bodies.

An object of this invention is to provide a cutting device using anultrasonic vibration system for an automatic lathe as mentioned above,even if the cutting device only has a slight space between tool bodies.

The cutting device of this invention is provided with a torsionaltransducer attached to the side of a tool body, preferably via anamplifier horn, so that the torsonal transducer serves to apply atransverse vibration to the tool body. The torsional transducer relativeto this invention can be adapted to the automatic lathe as indicated byreference numbers 26 to 30 in FIG. 2 wherein the transducers 26 to 30are attached to the tool bodies 21 to 25 in a manner so as extended in adirection perpendicular to a plane of the paper.

The features and advantages of this invention will become more readilyapparent from the following detailed description with reference to theaccompanying drawing, in which:

FIG. 1 is a side view of a cutting device according to the priortechnique;

FIG. 2 is a front view of an automatic lathe using an ultrasonicvibration system according to this invention;

FIG. 3 is a perspective view of a cutting device of an ultrasonicvibration system embodying this invention;

FIG. 4 is a side view of the cutting device of FIG. 3; and

FIGS. 5 and 6 are exaggerated side views of the prior cutting devicewherein the action of the tool and workpiece is more clearlyillustrated.

The cutting device illustrated in FIGS. 2 to 4 comprises a tool 31having a bar-shaped body 31a and a chip 35 mounted on the front end ofthe tool body 31a, and a torsional transducer 32 of convenient typewhich comprises a cylindrical ferrite core, a coil 40 attached to thecore, and a ferrite pole 41 inserted through the assembly of the coreand coil. The cutting device preferably involves an amplifier horn 33connected with the ferrite core and attached to the side of the toolbody 31a by soldering or means of threaded screws. The attachingposition of the horn 33 to the tool body should be a nodal point ofvibration of the tool body. Though the transducer 32 is here connectedthrough the horn with the tool body, it may be connected directly withthe tool body at a nodal point of vibration. The cutting tool 31 has twoset pins 34 in order to set the tool body 31a to a tool holder (notshown). The set pins 34 are attached to the tool body 31a at the nodalpoints of vibration of the tool body. The pins may be fixed to the sideof the tool body, although we prefer to pivot the tool body with the pinend rotatably inserted into a journal bore formed in the tool body sideand if necessary, to lubricate it by a graphite or molybdenum disulfide.

In the cutting operation, the turning center of a workpiece 36preferably agrees with and is aligned with or lies in a neutral plane 37of the nodal points of vibration and the cutting edge of the chip 35.

The chip 15 of the prior cutting tool as shown in FIG. 1 is attached tothe front end of the tool body with its cutting edge parallel to acentral plane 17 apparently defined to the middle portion of the toolwidth and deviating slightly from a true neutral plane 17'. Accordingly,the cutting edge of the prior cutting tool is vibrated with an errorangle to a tangential direction of the rounded surface of the workpiece16, because a quantity of the tool body is distributed asymmetrically tothe central plane by the cutting chip being one-sided, whereby thecutting edge is really vibrated in a direction indicated in FIG. 5 by anarrow line 18. In this case, in order to compensate for the vibratingdirection of the cutting edge, the workpiece must be adjusted to aposition as indicated in FIG. 5 by a dotted line 16', or the tool bodymust be inclined as illustrated in FIG. 6 so as to align the vibratingdirection of the tool with the tangential direction of the workpiece.Nevertheless, such compensation is unsighted and very difficult toperform.

In contradistinction with the above-mentioned prior technique, thecutting tool of this invention has a cutting edge effectively vibratedfor an elongated amplitude as illustrated in FIG. 4 by a referencenumber 39, because the front end portion 38 of the tool body is made ina thickness thiner than that of the other portion of the tool body. Ofcourse, the top end portion 38 may be made with a width narrower thanthat of the other portion of the tool body. Such a cutting tool resultsin improved cutting speed.

Furthermore, though the vibration of the cutting edge is generallydamped due to the cavitation generated as cutting oil supplied to thecutting edge avoidably flows to the supported portion of the tool body(cavitation in this case means that the vibration of the solid member isclamped by liquid vaporized in expansion as the liquid material isbrought into contact with the solid member under ultrasonic vibration soas to produce the vacuum space between both materials).

The cutting tool of this invention as shown in FIGS. 3 and 4conveniently includes a stepped form which prevents the flowing of thecutting oil toward the based portion of the tool body, so that theeffective vibration of the cutting edge is maintained. I

This invention also contemplates the use of a plurality of torsionaltransducers which, though not shown in the drawing, are attached to thetool body at nodal points of vibration, if necessary, via a plurality ofhorns.

We claim: 1. A cutting device in an ultrasonic vibration systemcomprising:

an elongated tool body having a symmetry plane through the center ofsaid body; means forming a cutting edge at a front end of said bodysubstantially at said plane; means for mounting said body so that thenatural transverse bending vibration mode of said body has nodal pointslying in said plane whereby said plane coincides with the neutral planeof vibration of said body;

a torsional transducer operatively coupled to said body with its axis oftorsional vibration lying in said plane and transverse to thelongitudinal extension of said body at one of said nodal points; and

an amplifier horn interposed between said body and said transducer totransmit bending vibration from said transducer to said body.

2. The cutting device defined in claim 1 wherein a plurality of suchtransducers and respective amplifier horns are provided at respectivenodal points along said body.

3. The cutting device defined in claim 1 wherein said body has a frontend portion of a thickness thinner than that of the rest of said body soas to increase the amplitude of said cutting edge in a directiontransverse of said body.

1. A cutting device in an ultrasonic vibration system comprising: anelongated tool body having a symmetry plane through the center of saidbody; means forming a cutting edge at a front end of said bodysubstantially at said plane; means for mounting said body so that thenatural transverse bending vibration mode of said body has nodal pointslying in said plane whereby said plane coincides with the neutral planeof vibration of said body; a torsional transducer operatively coupled tosaid body with its axis of torsional vibration lying in said plane andtransverse to the longitudinal extension of said body at one of saidnodal points; and an amplifier horn interposed between said body andsaid transducer to transmit bending vibration from said transducer tosaid body.
 2. The cutting device defined in claim 1 wherein a pluralityof such transducers and respective amplifier horns are provided atrespective nodal points along said body.
 3. The cutting device definedin claim 1 wherein said body has a front end portion of a thicknessthinner than that of the rest of said body so as to increase theamplitude of said cutting edge in a direction transverse of said body.